Victory, 22, of Albers, Ill., was examined and moved to Brooke Army Medical Center, where acute respiratory illness was diagnosed. She died at 4:51 p.m. Thursday, her parents by her side.

Victory's death is the first since 2009 at Lackland, which has had about a dozen since 1986. The last airman to die was Keith Mylott. In 2007, Paige Renee Villers, 19, of Norton, Ohio, fell victim to a flu strain that has long plagued boot camps.

BAMC spokesman Dewey Mitchell said physicians suspect Victory died of viral encephalitis caused by an adenovirus. Her health deteriorated rapidly June 25, when she struggled to breathe and fell into a coma, Mitchell said.

The cause of death was determined to be respiratory failure due to encephalitis. The family declined to have an autopsy performed, but BAMC sent tissue samples to the Centers for Disease Control and Prevention in Atlanta for examination.

Encephalitis is inflammation of the brain.

“After no improvement for several days and discussion with the family regarding no reasonable hope for recovery, the patient's family made the difficult decision to request removal of artificial means of life support on (Thursday),” said Dr. (Lt. Col.) Pedro Lucero, who led a team of intensive care specialists. “The patient died shortly thereafter.”

Lackland spokesman Jerry Proctor said there have been no virus outbreaks in Victory's flight or among other recruits on the base.

The San Antonio Metropolitan Health District's chief epidemiologist said there are no virus problems in the city.

But a BAMC doctor and Roger Sanchez, the epidemiologist, said adenoviruses could cause inflammation of the brain, as can West Nile virus and St. Louis encephalitis.

“It could be a multitude of organisms that caused encephalitis, many different kinds, and they may never know,” Sanchez said.

At first uncertain of what caused Victory to become ill, Lackland cleared her dormitory and decontaminated it using a “fog” of chemical disinfectants, Proctor said, calling the action “standard protocol.”

Lackland in recent years has coped with occasional outbreaks of adeno serotype 14, a virulent and highly contagious disease that has struck hundreds of airmen in training here.

Questions arose about the problem in the wake of Villers' illness. Two months before she died, Lackland reported an outbreak of “boot camp flu,” as adeno serotype 14 is known. The disease struck 100 airmen, with 17 hospitalized. Hundreds more were sickened in the coming months, 245 of them from adenovirus 14.

Doctors aren't sure if Victory was hit by adenovirus 14, but her initial symptom — a headache — was the same suffered by Villers, who later fell into a coma after suffering a seizure. Villers ultimately died of pneumonia complications.

An Air Force military trainer Friday night described Victory as quiet and unassuming, “a good follower” who helped other recruits with their tasks.

“She always met the challenges. She was among 10 trainees faced with a memory challenge and she was the only one who got every challenge question right,” said Staff Sgt. Michael Patterson, 32 and a native of Patterson, Mo.

“I was surprised by how quiet she was in the environment, but she showed confidence and was modest with what she could accomplish,” he said. “And when it was time for her to do what she needed to do, she had that confidence and did what was necessary without hesitation.”